body {
    font-family: '华文楷体', '楷体', serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    background: #3e2723 url('data:image/svg+xml,<svg viewBox="0 0 100 100" xmlns="http://www.w3.org/2000/svg"><text x="-10" y="70" font-size="85" fill="%2348342e" opacity="0.15">史</text></svg>') fixed;
    background-size: 20%;
    color: #4a342e;
}

.container {
    background: rgba(237, 225, 199, 0.96);
    padding: 2.5rem 3rem;
    border-radius: 4px;
    border: 2px solid #6b4f4a;
    box-shadow: 0 10px 30px rgba(0,0,0,0.3);
    width: 90%;
    max-width: 450px;
    position: relative;
    overflow: hidden;
}

.container:before {
    content: "";
    position: absolute;
    top: 0;
    left: -10%;
    width: 120%;
    height: 100%;
    background: repeating-linear-gradient(
        45deg,
        transparent,
        transparent 15px,
        rgba(107, 79, 74, 0.1) 15px,
        rgba(107, 79, 74, 0.1) 30px
    );
    pointer-events: none;
}

h1 {
    text-align: center;
    margin: 1rem 0 2rem;
    color: #4a342e;
    font-size: 2.4em;
    text-shadow: 2px 2px 3px rgba(107, 79, 74, 0.2);
    letter-spacing: 4px;
    position: relative;
}

h1:after {
    content: "";
    display: block;
    width: 60%;
    height: 2px;
    background: linear-gradient(to right, transparent, #6b4f4a 30%, #6b4f4a 70%, transparent);
    margin: 1.2rem auto;
}

.form-group {
    margin-bottom: 1.8rem;
    position: relative;
}

label {
    display: block;
    margin-bottom: 0.8rem;
    color: #5d443f;
    font-size: 1.1em;
    letter-spacing: 1px;
}

input {
    width: 100%;
    padding: 1rem;
    border: 1px solid #9e8d89;
    border-radius: 3px;
    font-size: 1.1em;
    background: #f5f0e5;
    transition: all 0.3s ease;
    box-shadow: inset 0 2px 4px rgba(0,0,0,0.05);
}

input:focus {
    outline: none;
    border-color: #6b4f4a;
    box-shadow: 0 0 8px rgba(107, 79, 74, 0.3), inset 0 1px 2px rgba(255,255,255,0.2);
}
.captcha-group{
    display: flex;
    width: 114%;
    justify-content: space-between;
    align-items: center;
}
.captcha-group input{
    width:97%;
}
.captcha-group div{
    font-size: 24px;
    background: #ede1c7;
    border: 1px solid black;
    height: 50px;
    line-height: 50px;
    text-align: center;
    /*padding-left: 10px;*/
    margin-left: 5px;
    width:20%;
    margin-right: 30px;
}

#sub {
    width: 100%;
    padding: 1.2rem;
    background: linear-gradient(to bottom, #6b4f4a, #58413d);
    color: #ede1c7;
    border: 1px solid #453732;
    border-radius: 3px;
    font-size: 1.2em;
    cursor: pointer;
    margin-top: 2rem;
    letter-spacing: 3px;
    transition: all 0.3s ease;
    text-shadow: 1px 1px 2px rgba(0,0,0,0.2);
}

#sub:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
    background: linear-gradient(to bottom, #58413d, #46322e);
}

.container:after {
    content: "";
    position: absolute;
    bottom: -30px;
    right: -30px;
    width: 100px;
    height: 100px;
    background: url('data:image/svg+xml,<svg viewBox="0 0 100 100" xmlns="http://www.w3.org/2000/svg"><path d="M20,50 Q40,25 60,50 Q80,75 80,50" fill="none" stroke="%239C8D89" stroke-width="2"/></svg>');
    opacity: 0.3;
    transform: rotate(45deg);
}

@media (max-width: 768px) {
    .container {
        padding: 2rem 1.5rem;
    }

    h1 {
        font-size: 2rem;
        letter-spacing: 0.3em;
    }

    input {
        padding: 0.8rem;
    }
}